Evaluation the Antibacterial Activity of the Brine, Nisin Solution, and Ozonated Water Against E. coli O157:H7 in the Experimentally Local Produced Soft Cheese
Antibacterial activity of brine, Nisin, and ozonated water against E. coli O157:H7 viability in the experimentally local produced soft cheese (ELPSC) was conducted during the period from December 2019 till end of February 2020. The positive isolates were detected as 3 out of 25 samples (12%). Identification of E. coli O157:H7 from ELPSC pieces were confirmed by using selective agar, biochemical, and serological tests. The concentrations that used from each of brine (sodium chloride), Nisin solution, and ozonated water were 7% (w/v), 100 IU/mL, and 0.6 ppm, respectively. The initial mean values of the E. coli O157:H7 counts in the ELPSC pieces were 6.146 log10 CFU/g, the bacterial counts decreased significantly (P<0.05) from 6.146 (log10 CFU/g) at 0 hour (control) to 3.778, 4.380, and 4.544 (log10 CFU/g) after 2 h of contact time due to the antibacterial action of brine, Nisin solution and ozonated water, respectively at ambient temperature. The antibacterial activity of ozonated water at the concentration 0.6 ppm, Nisin solution at concentration 100 IU/mL alone after 2 h of contact time were reduce (2 log10) of bacterial population without complete inhibition of E. coli O157:H7 in ELPSC, decontamination of ELPSC by brine solution at concentration (7% w/V) for 2 h can be more effective compared to Nisin solution and ozonated water at ambient temperature, there was no increase in the inhibition level when the cheese samples were dipping in the brine solution for longer exposure time (6 h) at the same concentration.